RE: newbie question : one shot measurement

["Manoussakis, Adamandios via Tech-talk" <tech-talk at aps.anl.gov>]

I will also add that is the way we do it over at our lab.  We have a trigger record that processes and grabs the data after the physical trigger goes out.

-----Original Message-----
From: Tech-talk <tech-talk-bounces at aps.anl.gov> On Behalf Of Michael Davidsaver via Tech-talk
Sent: Thursday, March 24, 2022 9:11 AM
To: Jérôme Poincheval <poincheval at lpccaen.in2p3.fr>
Cc: tech-talk at -aps.anl.gov <tech-talk at aps.anl.gov>
Subject: Re: newbie question : one shot measurement

On 3/24/22 08:54, Jérôme Poincheval via Tech-talk wrote:
> 
> Hi tech-talk,
> 
> I am new to epics, and using it to read data from a keithley scpi multimeter.
> 
> I want to get one shot readings, not periodic ones. So, to trigger an 'on-demand' measurement, I write a value to the .PROC field of my passive record to trigger processing, then read the value.
> 
> This works well, but I wonder if there is a 'read-data-now' function in epics which I have overlooked ?

Not really.  Though I like to hide ".PROC" using a boRecord so that OPI widgets can automatically show "Measure" as a label.

eg.

> record(bo, "$(PORT):measure_v_dc") {
>     field(ZNAM, "Measure")
>     field(ONAM, "Measure")
>     field(FLNK, "$(PORT):measure_v_dc_") } record(ai, 
> "$(PORT):measure_v_dc_") {
>     ... as below
> }


> ##### excerpt from .proto file :
> 
> # one shot measurement
> measure {
>         ExtraInput = Ignore;
>         out ":measure:\$1?";
>         in "%f";
> }
> 
> 
> ##### excerpt from .db file :
> 
> # read dc voltage, triggered by putting a value to measure_v_dc.PROC
> record (ai, "$(PORT):measure_v_dc") {
>         field (DESC, "voltage/dc one shot measurement")
>         field (DTYP, "stream")
>         field (INP,  "@scpi_keithley_2000.proto measure(voltage:dc) $(PORT)")
>         field (SCAN, "Passive")
> }
> 
> 
> -- 
> Jérôme Poinchevalpoincheval at lpccaen.in2p3.fr      tel:02.31.45.29.87
> LPC Caenhttp://www.lpc-caen.in2p3.fr
>